An advertisement display frame is generally composed of an upper transverse strut, and lower transverse strut and an upright support, with an image being arranged between the upper and lower transverse struts. There are various kinds of transverse struts. Chinese utility model patent No. 200720038995.6, titled “transverse struts for an advertisement display frame”, discloses a combinational transverse strut which comprises a base with a bendable cover plate arranged thereon, wherein the cover plate is connected to the base at their middle portions, one of the base and the cover plate is operatively connected with support members at its both ends, and at least a spring clip is provided between the cover plate and the base, and is located between each support member and a fixed point. In the combinational transverse struts, the cover plate is arranged on the base, and the cover plate is bendable. When the cover plate is closed, the transverse struts assume a linear state, and hence the image setup by the transverse struts is flat. When the cover plate is opened, i.e., when its two ends are setup, the cover plate assumes an arc-shape, and hence the image setup by the transverse struts appear in an arc-shape under the effect of the cover plate. The combinational transverse struts of this kind may render the image flat, or render it in an arc-shape. Chinese utility model patent No. 200720043668.X, titled “a two-in-one arc-shaped or linear advertisement display frame”, discloses a solution in which a lower transverse strut is another kind of combinational transverse strut, i.e., a base so-called easy-to-set piece. This transverse strut comprises a scrolling cylinder which has a base body and a bendable overlay plate located in front of the base body. The base body is fixedly connected to the middle portion of the overlay plate. Two support members are respectively arranged between the base body and the overlay plate, and are respectively located at the two sides of the middle fixed point. The above two kinds of combinational transverse struts can be setup by support members through setting up two ends of the cover (overlay) plates such that the cover (overlay) plates assume an arc-shape, and a large arc-shaped display frame may be obtained through putting together a plurality of transverse struts. In Chinese Patent No. 200720043668.X, it is proposed that two adjacent arc-shaped overlay plates of two transverse struts are connected therebetween via inserts. The two transverse struts are connected by means of inserting the two ends of the insert into the positioning grooves of the two adjacent overlay plates. Nevertheless, this connection is not secure, and in practice applications, operation of fixing the inserts onto the overlay plate through screws is inconvenient. Furthermore, the inserts are small and separate parts, which are inconvenient to storage and hence are likely to miss. Furthermore, when two ends of the overlay (cover) plate is set up, it is necessary to insert a finger into the space between the base body (base) and the overlay (cover) plate so as to set up the support member, hence leading to a troublesome operation since the space is limited.